.taiji {
  width: 100px;
  height: 100px;
  border-width: 2px 2px 50px 2px;
  border-style: solid;
  border-color: black;
  border-radius: 100px;
  position: relative;
}

.taiji:before,
.taiji:after {
  content: '';
  position: absolute;
  width: 10px;
  height: 10px;
  background-color: white;
  border-radius: 50px;
  border: 19px solid black;
  left: 0;
  top: 50px;
  transform: translateY(-50%);
}

.taiji:after {
  left: unset;
  right: 0;
  background-color: black;
  border-color: white;
}
